Bacteria have been found to have the ability to store "memories" and pass them down through inheritance
Memory in various forms and types is characteristic of all higher animals. However, American scientists have found that even the simplest microorganisms, such as bacteria, have similar memories.
The researchers noticed that bacteria that had experience of swarming, that is, collective movement on the surface with the help of flagella, subsequently more effectively participated in this type of movement. But bacteria do not have neurons, synapses and nervous system that would ensure the formation of memories, as in humans. To understand why this happens, decided experts in the field of molecular biology from the University of Texas at Austin (USA).
In their work, which was published by the journal Proceedings of the National Academy of Sciences, scientists performed more than 10 thousand analyses and found that in bacteria Escherichia coli (Escherichia coli), the trigger for "remembering" information about the forms of behaviour, which can later be activated in response to certain stimuli, is the level of cellular iron.
"Bacteria don't have a brain, but they are able to receive information from their environment. If they encounter these conditions frequently, they can store information about it and quickly access it later," explained the study's lead author Souvik Bhattacharyya.
Iron is one of the most abundant chemical elements on earth, playing a central role in cellular metabolism. In single, freely migrating bacteria, iron levels vary. Observations have shown that bacteria with low iron levels are more active and swarm more efficiently. In contrast, microorganisms forming a biofilm, i.e. a layer of bacteria on a surface, were characterised by high cellular iron levels. A balanced level of iron was also characteristic of antibiotic-resistant bacteria.
As the researchers found out, this memory of iron is passed on by the mother cell to the daughter cells until at least the fourth generation, and if you change the iron levels artificially, it can persist much longer.
"Before the appearance of oxygen in the Earth's atmosphere, early cellular life forms utilised iron in many processes. This element is crucial not only for the origin of life on our planet, but also for its evolution. It makes sense that cells utilise iron in this way," Bhattacharya added.
Scientists believe that the bacteria's "memory" is triggered when iron levels are low and this triggers a swarming process in which microorganisms begin to move quickly in search of environments with higher iron levels. When the level of iron is high, the "memory" suggests: this is a favourable environment, suitable to stay in it and form a biofilm.
According to the authors of the paper, their discovery will help in the development of more effective strategies to prevent the spread of bacterial infections. In addition, new knowledge about the behaviour of bacteria will be useful in the fight against antibiotic-resistant microorganisms.